Press for the manufacture of continuous web material



July 15, 1952 w. J. FISCHBEIN 2,602,960

PRESS FOR THE MANUFACTURE OF CONTINUOUS WEB MATERIAL Filed Nov. 18, 19495 Sheets-She et l lav enboz hf Jfwch bez lvf y 1952 w. J. FISCHBEIN2,602,960

PRESS FOR THE MANUFACTURE OF CONTINUOUS WEB MATERIAL Filed Nov. 18, 19495 Sheets-Sheet 2 I I U Zfzzv 61232501 AZ Jl'iacjzeazz PRESS FOR THEMANUFACTURE OF CONTINUOUS WEE MATERIAL July 15, 1952 w. J. FISCHBEIN 5Sheerls-Sheet 3 Filed Nov. 18, 1949 July 15, 1952 w. J. FI'SCHBEIN2,602,960

PRESS FOR THE MANUFACTURE OF CONTINUOUS WEB MATERIAL Filed Nov. 18. 19495 Sheets-Sheet 4 y 1952 w. J. FISCHBEIN 2,602,960

NTINUQUS WEB lVL YIERI1-\L PRESS FOR THE MANUFACTURE OF 00 v 5Sheeis-Sheet 5 Filed Nov. 18, 1949 2. L721) 6.270%? 2] difabelubmPatented July 15, 1952 PRESS FOR THE MANUFACTURE OF- CONTINUOUS WEBMATERIAL William James Fischbein, London, England, as-

signor of one-half to British Artificial Resin Company Limited, London,England Application November 18, 1949, Serial N 0. 128,199

' In Great Britain November 24, 1948 4 Claims.

This invention relates to caterpillar presses of the character describedin British patent specification No. 595,423 (of which the presentcompany are copatentees) for the manufacture, under heat and pressure,in continuous web or long sheet form of wallboard, sheeting or panellingor like material (hereinafter called wallboard) having a large surfacearea in relation to thickness, an aim of the invention being to providea machine essentially capable of manufacturing such wallboard from a,mixture of a discrete filler, such as sawdust or other comminutedfibrous or cellulosic or other material bound with a thermo-settingplastic, in such a manner that the product is of uniform gaugethroughout Without waves or zones of overcompression or transversesurface marks.

In machines of the character indicated where the material undertreatment is pressed between metal bands'backed by lower. and upperplaten roller chains, running on pressure applying rails orbeds,difiicuities arise, particularly when treat.- ing a mixture orcomposition including a thermo: setting hinder or other bonding materialinrefe erence to which curing or. setting starts at, an a y sta t e h aa d. ess treatme t,

It wi be a pre ia d h if pr ssure is ad- Mi ly a pl e ver a. p o eperiod as i t e a e Whe e. th ress ecksco se er their en th 91. ravel,ina u in i deferred to he 11d. of th irsatm ni n ns q en r m reat Pr s ew uld h ve eb e l to secure the required consolidation and gauge, if atall practicable, owingv to the fact that the material will have reachedan advanced curing stage.

For these reasons it is essential to apply the pressure for bringing thematerial to its iinal gauge and consolidation during a relatively shortlongitudinal travel in the initial stage when the material first comesb'etween th'pressure' elements and which may conveniently be referred toas a squeezing zone, and thereafter to maintain pressure to preventrecovery or reactive swelling and ensure a uniform holding. pressureuntil the curing or setting of the binder compon ent has gone beyond therecovery stage.

In utilising a' cat'erpillar press. to e'fl 'ect the essential squeezingzone treatment a problem arises in that the platens offone trackinturni'ng into the rectilinear pathparallel to the platens of the othertrack are liable to impress irregu larities or transverse marlgs' uponthe material under treatment. The problem is twofold: firstly, theleading edge of the platens" in turning" is liable to dig. into'themetal band and cause local transverse overcompression or a mark to beimpressed on the material, and secondly; the metal band is liable totake a permanent set. The re active pressure of the material in thesqueezing zone flattens the band against the faces ofadjacent angularlydisposedplatens and the bending at the facing angle is liable to strainthe metal of the band beyond its elastic limit.

The invention is directed tothe solution of this problem by adoptingapositioning of the rollers of the upper chain (assuming it tobe thechain which turns into the rectilinear path in the said squeezing zone)with their axes over the junctions between the platens and providingarunning rail or bed form for the rollers at the squeez ing zone whichconstrains the platens in turning into the rectilinear path to travel onan arc or curvature of such radiusthat the flexure of the band as it isflattenedin the squeezing zone I against the angularly disposed faces.is well within the elastic limit, and further thatthe gap between theplatens in making said turn is such that on the one hand, the band inthe locality assumes a convex curve which is within the criticalcapacity of recovery to bending of the metal, and on the other, iscapable of supporting the reactive pressure of the material. Toencompass this latter feature it. is essential according to theinvention to arrange the linkage of the platens so as to provide a gapbetween adjacent platen edges when in the rectilinear position such thatthe band lies across it with insignificant concave deflection, while atthe critical turning point in the squeezing zone, the gap widens toallow a free bowing of the band about a radius well within the elasticlimit of the metal. The existence of the gap between platen edges, inthe rectilinear run also accommodates heat expansion and debris which,if collected between platen edges, would set up undue strain under thepressure. The gapping may. beprovided by amply radiusing the platenedges with a clearance m rear which is merely sufficient to accommodatedebris and allow for expansionj The invention also comprises a compositeroller platen link band or chain havi'n'ga, senes'srtransverse sets oflinks each link of wlii hjbe'ars" a roller at each end, the sets beinconnected to: gether by intermediate sets of plain linksalteratingtransversely. with the rollered links to which they are pivotallycoupled, and platen plate members for each set of rollered and plainlinks extending transversely from side to. side of the composite chainanddisposed to afford a small gap between the leadingedge of each platenand the trailing edge of the next, with the width of the gap determinedaccording to the gauge of the metal band, and the characteristicsthereof such that under pressure the concave deflection of the band atthe gap does not exceed a few thousandths of an inch when the platensare in the rectilinear path, the relative arrangement of the roller andlink pivotal axes and the gaps being such that the central planes of thegaps substantially contain the said axes.

The above form of chain is employed for that chain (preferably the upperone) the platens of which turn into the rectilinear path in the saidsqueezing zone, while the other chain may have the same characteristics,but since its platens can assume the rectilinear path before enteringthe squeezing zone the precautions referred to above are not soimportant. The platens of this other (lower) chain are convenientlyprovided at their outward ends with upstanding flanges to provide, whenthe chain is running in the rectilinear path, continuous deckle edgeswithin which the metal bands and the platens in the pressure lap of thefirst-mentioned chain are housed.

, According to one arrangement of the backing or running beds for theplaten chain rollers the lower bed is mounted as a fixture and the upperbed and chain is mounted for vertical displacement, and this arrangementwill be assumed for the purpose of further description andexempliflcation of the invention.

According to the invention a backing or running bed for the upper chainis floatably mounted for vertical displacement and equalised pressure isbrought to bear throughout the pressure lap hydraulically to effect suchdisplacement.

In one form the bed comprises a series of massive transverse beamscarrying a set of inverted rails corresponding with and acting asrunning tracks for the link rollers suspended from the pistons ofhydraulic cylinders in hydraulic communication one with another andconnected to a common pressure source.

The bed for the lower lap may be of similar massive transverse beam andrail construction and it is preferred that the beds should operate inopposed relation by mounting the beams between the jaws of massivevertical brackets located at the sides of the pressure lap so that suchbrackets under pressure function in tension.

The machine according to the invention may be built to operate on aprepared mat of material fed on the lower band to the pressure lap,according to one or other, or alternatively either, of the modeshereunder:

1. Producing products by maintaining a constant; pressure on the mat inthe machine and providing for products of different final gauge byvarying the thickness of the mat presented for pressure.

2. Operating upon mats of constant thickness and providing for pressuresof selectable value whereby products of different thickness and densityresult.

3. Combining the adjustments available under 1 and 2 above.

The invention will be further described hereunder with respect to amachine for manufacturing wall boarding in continuous wall form from alayer or mat of a mixture of sawdust or the like and a proportion of athermosetting binder such as phenol formaldehyde or urea formaldehyde,which has been subjected prior to its entry into the machine to a heattreatment, preferably by radio frequency electric field.

In the accompanying drawings:

Figure l is a side elevation of a machine for carrying out; the presentinvention.

Figure 2 is a plan view of the machine shown in Figure 1.

Figure 3 is to the right of the centre line an end elevation of the samemachine viewed from the left of Figure 1 and with the caterpillar chainsand metal bands removed, and to the left of the centre line a sectionalelevation on the line 33 of Figure 1.

Figure 4 is a side elevation partly in section showing in more detailthe feed end of the machine and the mat of board-forming materialpassing into the squeezing zone.

Figure 5 is a fragmentary isometric view of the link construction of theplaten chain with the rollers removed.

Figure 6 is a plan view of a length of the platen chain showing the linkarrangement.

Figure 7 is a detail side elevation of the pressure rail arrangement andtransverse supporting beams.

Figure 8 is a plan view of the arrangement shown in Figure 7, and

Figure 9 is an end elevation of the arrangement shown in Figure 7 givinga side elevation of one of the transverse supporting beams.

In carrying the invention into eifect as described by way of example, asuitable foundation is provided on which are mounted two sets of massivebrackets I, a set being located at each side of the machine. Thesebrackets each have an inwardly projecting foot 2 and an inwardlyoverhanging head 3, the sets being positioned in pairs facing oneanother. The upper ends of the pairs of brackets are tied across bytransverse girders 4.

Extending between and supported upon the foot portions of each pair ofbrackets l is a massive beam (or beams) 5 for supporting a bed 6 overwhich runs the active or pressure lap of the lower of two endless chainsA and B of pressure applying platens l8 and 20.

Similar but inverted beam members 1 are provided for the upper bed orabutment 8 for the platens of the pressure lap of the upper endlesschain A of platens [9. These upper beams l are mounted for displacementunder the pressing operation towards the lower bed and are suitablyguided at their outer end in vertical slideway members 9 which mayconveniently be mounted on the inner sides of the brackets I. The beamsl are slung from or acted upon towards each end by the pistons ill ofhydraulic cylinders l I carried at the underside of the bracket heads 3.In the machine illustrated (see especially Figures '7 and 8), the beamsl are connected in pairs by bridge members 10, the hydraulic cylinderpistons It! being applied centrally of the bridge members; thus eightbeam members are served by four hydraulic cylinders II on each sidecorresponding with each set of brackets I (see Figure 2).

Upon or in each of the lower and upper sets of beams 5 and 1 thepressure beds 6 and 8 are formed by massive longitudinal rails 12 andI3, such being adopted for the beds as the most suitable form ofconstruction for co-operation with stout running or anti-frictionrollers M with which the platen chains A and B are provided as describedhereafter.

The rails l2 and I3 may be provided with hardened wear faces H and 12with which the rollers l 4 have contact. The board-forming material' Eis treated between: lower. and. upper endless metal bands D and F whichpassbetween the active horizontal .and parallel laps; of the lower andupper platen. chains A and B.

At each end of. the machine, turning point chain wheel members orassemblies |5- are mounted on transverse shafts It: running in suitablebearings l1 carriedin supports lfl'from; the machine foundation, theshafts l5, bearing I1 andv supports l8 being: shown; only on the left ofFigure 2. The longitudinal distance; between the axes of the chain wheelmembers Is for the upper chain A may be somewhat less than that for thechain wheel members for the lower chain B as it is; convenient toarrange thelower chain B protruding beyond the ends of the upper chainA, especially at the feed end of the machine, in order that the platens[9 of the lower chain will assume their horizontalrectilinear runposition before entering. the squeezing zone between the platens.

For a machine for making wide wall boarding (for example, 4 ft. wide)the platens l9 are carried by a composite link chain to overcome certaindiificulties in manufacture.

These composite link chains each comprise a series of transverse sets ofrollered links 2| and a corresponding series of transverse sets of plainor unrollered links 22. The sets of plain links 22 are locatedlongitudinally betweenthe sets of rollered links 2| and both-sets arepivotally connected together attheir adjacent ends by pivot pins orspindles 23 to constitute a hinged link chain with the plain linksintervening, transversely of the chain, between each pair of rolleredlinks. The pins or spindles, 23 do not extend across the whole width ofthe platen chain, but only across three widths of links as shown as a.group in Figure 5; in this way any transverse flexure of the platenchains does not cause binding between the pins or spindles 23 and theirassociated links 2| and 22.

The rollered links 2| each comprise a link, body 24 (see Figure 5.),towards the ends of which leg members 25 project toward the interior ofthe endless laps of the chain. On these leg members 25 bearings 26 areformed for the trunnions or spindles 21, of the stout rollers It. (seeFigures 4 and 6). Thus the rollers M are mounted in the transverseintervals between the rollered links 2| afforded by the interveningplain links 22, one trunnion of each, roller being supported in half thebearing in the leg of one link and the other trunnion in half thebearing in the leg of the next laterally adjacent link so that eachbearing 26 accommodates the two trunnions of adjacent rollers. The axesof the rollers I4 and the axes of the link pivots 23 lie substantiallyinv the transverse plane at the junction between the links. The bodyportion 24 on its inward side of each of the rollered links 2| has asprocket recess 28 for driving engagement by sprocket teeth 29 of thechain wheel assemblies I5.

The chain wheel assemblies l5 each comprise a series of sprocket tootheddiscs 30 spaced on their shaft l6 in planes aligned with thelongitudinal planes of the sets of rollered links 2|.

Each set of links 2| and 22 has transversely extending (from side toside of the pressure bed) the platen plates it of. heavy gauge welded orotherwise secured to and transversely bridging the links so that eachset of rollered and plain links becomes an integral unit with its platenplate IS. A heat insulating layer may be interposed between the platensand the links of the chain i order to increase thealife: of. the chainbearings. The, width.'(i;.e.'the dimension taken longitudinally of: the.machine) of the laten plates l9, more particularly those of the upperchain A, should be: made as short as constructionally convenient inorder to conform to. the radius of curved path (as referred to above anddescribedv hereinafter) required in the squeezing zone (see Figure 4).

flanges 3| which when mated on the straight run form upstanding,continuous deckle edges for'laterally confining the material E underpressure and housing the metal bandsD and F. This squeezing. zoneextends from the adjacent end of the rectilinear horizontal path of, theupper chain A to. a: point where the upper surface of the mat E ofmaterial for treatment comesunder pressure applying contact with theupper metal band F and the angle subtended by. this zone will vary withthe thickness. of the, mat fed in. As shown in Figure 4, the squeezingzone extends from point X to point Z.

The edges of adjacent platen, plates of the upper chain A when in theirrectilinear pressure path do not meet, a gap 32 being left between theiredges at theface. If the edges met so that the platens prescribed a.continuoussurface in the said rectilinear path, then the gap which ofnecessity is opened when. the platens are travelling in the curved path,would be sufliciently small to cause danger of the metal band being benton the angularly disposed platens as over a definite edge angle, as thereactive pressure of the material under treatment forces the adjacentportions of the hand against the said angularly disposed platen faces.

Hitherto. it has been. considered necessary to avoid gaps betweenplatens when on the straight runs of the chains in order to preserve acontinuous pressure surface. It has, however, been found that byproviding a small gap between platen facing edges in the straight runs,a suificien-tly large gap is furnished at the curved path in thesqueezing zone to enable the band in bending to bow in a curve of largeenough radius to avoid approaching the elastic limit of the metal of theband and imposing a permanent set in the band, the said bow constitutingan arched bridge across the said gap such as to sustain the imposedpressure.

The width of the small gap is also governed by the permissible widthwhen the band is lying (as a beam) across such gap in the rectilinearpath. If the gap is too wide under pressure there would be a concavedeflection of the band into the gap which would cause a discernibleconvex mark on the material. Therefore, in choosing the gap it must belimited to one which would not permit a concave deflection of more than,say, of the order of a few thousandths of an inch. Naturally the widthof the permissible gap will vary according to the thickness andresistanceto deflection of the metal band.

Each gap may be a throughway gap with radiussed outer edges as shown at33 in Figures 4 and 5, or by providing a sufiicient radius the requiredgap efiect may beattained without its penetrating throughout thethickness of the platen plates.

No gaps (as viewed in the straight run) between platen plates for thelower chain need be provided, since the platens-of the lower chain enterthe squeezing zone already in the rectilinear path and the problem doesnot arise; neverthe- The ends of the platens IQ of the lower chain. Bare upturned. in side 7 less, it is preferable t'o-provide' for gaps 34'(Fig ure 4) since they also avoid any expansion difficulties under heat,accommodate fragments of debris, and enable the same link constructionto be used for both the upper and lower chains. The active or pressurelap of the lower chain B is supported and guided in the horizontal pathby the chain rollers I4 running on the lower set of rails I2. The idleor return lap of the lower chain is conveniently supported by theprovision of a series of fixed axis rollers mounted below said lap(Figures 1 and 3).

The idle lap of the upper chain A is supported on light rails 36positioned below said lap and on to which the rollers of the links runas the upper chain links emerge from one chain wheel assembly and passtowards the other chain wheel assembly. In order that the rollers I4 ofthe chain links do not fall away or become displaced when unsupported orwhen the links are canted or inverted a pair of retaining pins 31 areprovided across the open end of each bearing 26 and are accommodated inholes 38 provided therein (see Figures 4 and 5). I

The upper chain A is mounted and proportioned such that its lower lapsags from its'chain wheel assemblies I5 and this sagging'portion at thefeed end of the machine is constrained to travel through the squeezingzone X-Z in a path of predetermined curvature.

This curved path is preferably provided by extending the forwardhorizontal portion 39 of the said upper (abutment) rails I3 into asmooth curve of large radius (or radii) and this curved part maycontinue toward the vertical axial plane of the adjacent chain wheelassembly.

The path of the platens I9 of the upper chain A with their rollers I 4running on the curved rail portion 39 guides the upper metal band Fthrough the squeezing zone X-Z, in such a manner that transverse linesof unequal pressure are avoided and the band is not subjected tostresses which would impart a permanent set. This effeet is broughtabout by co-ordinating the radius of the curved squeezing path with thegaps provided between platens having regard to the thickness or gauge ofthe metal band, the characteristic to bending of the metal and thepressure to be sustained. For example, with a tempered carbon steel bandof thickness of .024 inch employed in a machine developing a pressure ofthe order of 300 lbs. per sq. inch, the curved squeezing zone path forplaten 12 inches in width should have a radius not less thanapproximately 6 feet and the small gaps (taken in the straight run ofthe platens) should be about /8 of an inch across the adjacent end edgesof the platens and about inch including the radiussed edges of the facesof the platens, opening to a maximum in the squeezing zone of about ofan inch. Both the upper and lower metal bands may be the same but itwill be appreciated that as the lower band is operating under difi'erentconditions it may be of different metal and gauge, for instance it maybe of stainless steel and of any suitable gauge.

Both metal bands are supported on rotary guide drums (as shown in thecase of the upper band F on drums 40) appropriately positioned to leadthe band between the upper and lower platens, the lower band being laidupon the lower platens as they assume their rectilinear horizontal run.It is convenient to arrange for the lower band D to be extended on thefeed side to a mat laying or spreading station including a preheatingzone where the material is treated to radio frequency heating currents.Also the lower band D may extend beyond the output end of the machine todeliver the formed board for further processing, cutting up anddistribution. Thus as in the machine illustrated the guide drums for thelower band D are not shown. i

The upper band F is'led under the sag of the platens of the upper chainA to contact therewith in front of the maximum squeezin zone angle ofthe machine (see point Y in Figure 4). The traction efiect of the chainsupon the respective bands is suflicient to traverse the band along thebed at the same rate as that of the chains without independent drivingmeans.

The hydraulic cylinders II for bringin the operating pressure to bearupon the material through bed rails I3, platens I9 and metal band F, arehydraulically coupled together into a system and to a suitable source ofhydraulic pressure in such a manner that the pressure effected by thehydraulic pistons is uniformly distributed throughout the pressure beds.Adjustable limit or stop means are provided for the hydraulicdisplacement accurately to determine the gauge to which the material isreduced under the applied pressure. The hydraulic system and theadjustable limit or stop means used in conjunction therewith are notillustrated and may be of any convenient known character, the design ofwhich forms no part of the present invention, the essential being that apositive stop is provided to limit the downward movement of the pressurebeds so that the board is accurately gauged to the predeterminedthickness required.

Any suitable means for maintaining a heat treatment of the materialconcurrently with the pressure treatment between the pressure beds maybe provided. According to one mole the platens or chain links may beelectrically heated by resistance elements located or enclosed in theplatens.

Alternatively the heating may be done by radiant heaters situated closeto the platen faces on the return laps. For this purpose the return lapsof the metal bands may be supported in spaced relation to the returnlaps of the platen chains so that suitable heaters may be located inproximity to the platen faces on their return laps, to provide thenecessary heating. The means for maintaining or providing heat treatmentof the material under pressure is also not illustrated in theaccompanying drawings, since these means may be of any suitable knowncharacter and do not form part of the present invention.

After passing through the squeezing zone XZ determining the gauge andconsolidation of the material the parallel horizontal run of the platenchains maintains the pressure during the major or that part of thecuring period of the thermo-setting binder component of the mixturewhere there is any substantial tendency to recovery or reactive swellingof the material. Hence, the pressure bed I3 should extend for ten feetor such other length as required according to the curing period of thematerial and its properties of recovery and the rate of travel of theplatens.

At the delivery end of the machine the upper platen chain A may beguided as by the portions 4| of the rails I3 (Figure 1) to the adjacentchain wheel assembly in a curved path similar to that of the squeezingzone, but in this case the only precaution necessary is to arrange thatthe platens do not changedirection so abruptly as terial at the deliveryend of the upper chain and passes around the guide-drumlfl (oi-drums) ona return path to the feed-end of the machine.

The metal bands D and E-mayact directly on thematerial or through apaper, textile or other layer ofmaterial or foil. Forexample, a"continuous paper orother layermay be laidby any known means underthe-mat-of material'and between it and the lower'band. According to oneconvenient modethe -mat of material is spread upon a paper or other'w ebofthe same widtlras the finished-boarding at the laying -or-feedingstation, whence it passes supported uponthe cx tension of the lowermetal band tothe pressure applying platen chains, receiving on the wayat a suitable point a superimposed web "of paper or s the like. .Thusthe board Y as delivered comprises a core of'consolidatedboardforming'material sandwiched between preformed layers of covering orfinishing material integrally united to the core material. The means forproviding such surface layer are'not illustrated in the accompanyingdrawingsand do not-form a part of the present invention, suitable meansare, however, wellknown in theart.

The density of the boardis-controlledby the pressure adjustmenton thehydraulic --mechanism as well as being dependent on the type andparticle size of the moulding material, chiefly wood waste. Thethickness is controlled-by the same factors, and in addition, by thevolume or weight of moulding material whichis ;-delivered by the feedingdevice; It ispreferred -to keep the pressure at some constant'valuegreater than 200 lbs. per square inch, --and-approximately to adjust thethickness by the volume of moulding material delivered by the feedingdevice. The final thickness is imposed and gauged accurately by thecontrol of the previously mentioned adjustable limit or stop means onthe hydraulic mechanism, which may come into action towards the end ofthe squeezing zone.

Although the improved machine is primarily intended for the purpose oftreating a lparticular mass whether initially in dry-powder form or fedas a semisolid or plastic consistency, themachine may be used as a presswith or without heat, for the lamination ofjsheet materiaL-such asplywood, or other multipleusheets or webs including fabrics, feltedmaterial or thin metal or metallic sheets or webs.

I claim:

1. In a caterpillar press of the type in which material under treatmentis pressed between metal bands backed by upper and lower endless chainsof platens turning around chain wheels and led into rectilinear andparallel paths and backed by rectilinear bed means, where the material,until set, is maintained under pressure to prevent recovery or reactiveswelling after having been brought to final gauge and consolidationduring a relatively short longitudinal travel through a squeezing zonelocated in advance of the rectilinear path zone, the squeezing zoneextendingvfrom the point at which the upper band first makes contactwith the material to the point at which the upper band enters itsrectilinear path, the improvement including a long radius curved guidememberfor the upper platen chain and locatedtoeng-agesaid chainthroughout the extent of .the squeezing zone, pivotal connecting meansfor the chain links, roller means associated with the chain andengageable againstsaid bed meansin the rectilinear path and against saidguide member in the squeezing zone, the pivotal axis of each of saidconnecting means and the axis preach roller --means being disposed withrespect to the gap between eaeh-platen and the next such that theeentral plane-of each gap substantially contains said axes, saidgap-being such that when the platens are in their rectilinear path it-is-wid er than may be required to accommodate heat expansion andis-bridgeable by the said -upper band without appreciable deflection,andthe curvature of said guidemember and said width of said gap being sochosen that when the platens are traversingsaid guide member, each gapopens to a degree permitting the band, between the portions thereofwhich are pressedflat against the adjacentplatens by the reaction of thema- 1 terial in thesqueezing zone, to bend within the elastic limit ofthe metal and form an arched bridge spanning said cap and capable ofsupporting said pressure, whereby the material when compressed in thesqueezing zone or in the rectilinear lap IBCSlYES'IlO mark appreciableto the'eyein'the region ofsaidgap.

,2. In a caterpillarpress of the type in which material undertreatment'is pressed between metal bands backed by upperand lowerendless chains of platens turning around chain wheels and led intorectilinear and parallel paths and backed byrectilinear bed means, wherethe material, until set, is maintained under pressure to I preventrecovery .or reactive swellingafter having been brought tofinal gaugeandconsolidation'during a relativelyshort longitudinal'travel "through asqueezingzonelocated in advance of the rectilinearpath zone, thesqueezing zone extendingfrom. the pointat which the upper band firstmakes contact with the' material to-the point at which the .upper bandenters its rectilinear path, the improvementincluding a to form saidchains, rqller means carried, at

each end of each alternatelinkaround the chain and engageable againstsaid bed meansinthe rectilinear path and against said guide memher inthe squeezing zone, the pivotal axis of each of said connecting meansand the axis of each roller means being disposed with respect to the gapbetween each platen and the next such that the central plane of each gapsubstantially contains said axes, said gap being such that when theplatens are in their rectilinear path it is wider than may be requiredto accommodate heat expansion and is bridgeable by the said upper bandwithout appreciable deflection, and the curvature of said guide memberand said width of said gap being so chosen that when the platens aretraversing said guide member, each gap opens to a degree permitting theband,

11 between the portions thereof which are pressed flat againsttheadjacent platens by the reaction of the material in the squeezing zone,to

, bend within the elasticilimit of the metal and form an arched bridgespanning said gap and capable of supporting said pressure, whereby thematerial when compressed in the squeezing zone or in the rectilinear lapreceives no mark appreciable to the eye in the region of said gap.

3. In a caterpillar press of the type in which material under treatmentis pressed between metal bands backed by upper and lower endless chainsof platens turning around chain wheels and led into rectilinear andparallel paths and backed by rectilinear bed means, where the ma- 1terial, until set, is maintained under pressure to prevent recovery orreactive swelling after having been brought to final gauge andconsolidation during a relatively short longitudinal travel ,to form theendless chains, pivotal connecting means for connecting the chain linkstransversely in said sets and for connecting said sets to form saidchains, roller means carried at each end of each alternate link aroundthe chain and engageable against said bed means in the rectilinear pathand against said guide member in the squeezing zone, the pivotal axis ofeach of said connecting means and the axis of each roller means beingdisposed with respect to the gap between each platen and the next suchthat the central plane of each gap substantially contains said axes,said gap being such that when the platens are in their rectilinear pathit is wider than may be required to accommodate heat expansion and isbridgeable by the said upper band without appreciable deflection, andthe curvature of said guide member, said width of said gap and thedistance of the pivotal axis of the connecting means from the operativefaces of the platens being so chosen that when the platens aretraversing said guide member, each gap opens to a degree permitting theband, between the portions thereof which are pressed flat against theadjacent platens by the reaction of the material in the squeezing zone,to bend within the elastic limit of the metal and form an arched bridgespanning said gap and capable of supporting said pressure, whereby thematerial when compressed in the squeezing zone or in the rectilinear lapreceives no markappreciable to the eye in the region of said gap.

treatment,

4. In a caterpillar press ior continuously applying heat and pressure toa material to'be treated upper and lower endless chains turning aroundchain wheels, said chains comprising transverse sets of pivotallyconnected links, platens carried by each of said transverse sets oflinks, pivotal connecting means between each link of each set andbetween each transverse set of links, roller means carried at each endof each alternate link, rectilinear rails located in alignment with saidroller means adapted to back and apply pressure to said chain throughsaid roller means, means for applying pressure to the rails backing oneof said endless chains, limit means influencing said pressure, means toprevent said one endless chain being moved under said pressure beyond apredetermined distance towards the other chain to gauge the materialunder long radius curved guide means formed as a continuation of saidrectilinear rails and backing said upper chain to constrain the platensof said upper chain to approach the platens of said lower chain along acurved path,

and endless metal bands operatively associated with the platens locatedto be interposed between the platens and the material under treatmentboth when the platens are backed by the rectilinear rails and when theplatens are in said curved path, the pivotal connecting means betweenthe chain links and the axis of each roller means being arranged to lieon the central longitudinal plane of the gap between the edge of eachplaten and thenext, said platens being dimensioned to give to said gap awidth when the platen faces are in rectilinear alignment greater thanthat required for the accommodation of heat expansion of said platensand said chain links, the dimension of said gap being further regulatedwith respect to the radius of said curved guide means such that when theplatens are angularly disposed in said curved path each gap opens to adegree to allow said metal band to form an arched bridge over said gapwhich will support the reactive pressure thereon of the material undertreatment.

WILLIAM JAMES FISCHBEIN.

REFERENCES CITED The following references are of record in the file ofthis patent: I

UNITED STATES PATENTS

